package acm;

import java.util.Scanner;

public class 未名湖边的烦恼 {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        int m = in.nextInt();
        int n = in.nextInt();
        System.out.print(result(m,n));
    }
    public static int result(int a,int b){
        if (a<b){
            return 0;
        }
        if (b==0){
            return 1;
        }
        else {
            return result(a-1,b)+result(a,b-1);
        }
    }
}
